1. Field of the Invention
The present invention relates to an agent composition for detecting a redox reaction. More particularly, the present invention relates to an agent composition that can suppress or remove the adverse influence of iodine which is liberated when such an agent for detecting a redox reaction contains iodic acid or an iodate for removing a reducing substance.
2. Description of the Related Art
Various diagnostic agents are known for detecting various substances in a body based on redox reactions.
Since a reducing substance present in a reaction system, such as ascorbic acid, interferes with the redox reaction, many measures for preventing or avoiding such interference have been proposed. Japanese Patent Publication No. 15280/1989 (corresponding to Japanese Patent Kokai Publication No. 109595/1981) discloses pretreatment of a sample to be analyzed with iodic acid or an iodate at pH of 3 to 5. Japanese Patent Publication No. 4861/1990 (corresponding to U.S. Pat. Nos. 4,743,559 and 4,957872 and EP-A-037 056) discloses a diagnostic agent for detecting a redox reaction which can avoid the influence of ascorbic acid by the presence of iodic acid or an iodate.
However, the pretreatment of the former method makes the analysis (diagnostic procedures) complicated and is less preferred.
When the latter diagnostic agent, which removes the reducing substance with iodic acid or the iodate, an accurate diagnosis cannot be performed by using a conventional Trinder's reagent. This is because the iodine which is liberated through a reaction of the iodate with ascorbic acid serves to oxidize the Trinder's reagent and thus colors the background to give a false positive result.
At pH of less than 5, it is possible to remove not only ascorbic acid but also other reducing substances such as bilirubin, cysteine or aminopyrin with an iodate. However, at pH of less than 5, an influence of the liberated iodine increases so that, with any color reagent, it is impossible to avoid this influence. When pH is further decreased, the iodine is liberated in the absence of ascorbic acid and oxidizes the color reagent to color the background of a test piece.
As explained above, a cause of the adverse influence on the diagnostic agent is an oxidizing property of the liberated iodine.
If there were a method for quickly capturing the liberated iodine before it influences the color reagent, the adverse influence of the liberated iodine could be excluded.